The buffer layers used in this study included an AlN/3C-SiC composite film
stack and a single AIN layer. 3C-SiC in the composite film stack prepared b
y the two-step process functioned better as a buffer layer than that prepar
ed by direct epitaxial growth. The composite buffer prepared by this method
was compared with the single AIN buffer. The GaN films grown on the compos
ite buffer were significantly less susceptible to film cracking than those
grown on a single AIN buffer. Photoluminescence evaluation showed that the
GaN films deposited on the composite buffer were narrower in full width at
half maximum than those deposited on a single buffer. However, the GaN and
AlGaN films grown on top of the single AIN buffer showed smoother top surfa
ce and resulted in higher electron mobility in the AlGaN/GaN heterojunction
. Surface and film qualities of the GaN films grown on the composite buffer
were improved by insertion of an AlGaN/GaN superlattice. (C) 2001 Elsevier
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